Carbon nanotube electrode for perovskite solar cell with improved reflectivity, manufacturing method therefor, and perovskite solar cell including same

Abstract

The present application provides a carbon nanotube electrode for a perovskite solar cell with improved reflectivity, a manufacturing method therefor, and a perovskite solar cell including same. More specifically, the present application provides a carbon nanotube electrode for a perovskite solar cell with improved reflectivity, a manufacturing method therefor, and a perovskite solar cell including same, wherein the carbon nanotube electrode exhibits improved reflectivity, prevents moisture penetration, and migrates incomplete contact through surface coating of carbon nanotubes, thereby increasing the efficiency of the perovskite solar cell.

Description

Carbon nanotube electrode for perovskite solar cells with improved reflectivity, method for manufacturing the same, and perovskite solar cell including the same

[0001] The present invention relates to a carbon nanotube electrode for a perovskite solar cell with improved reflectivity, a method for manufacturing the same, and a perovskite solar cell comprising the same. More specifically, the present invention relates to a carbon nanotube electrode for a perovskite solar cell with improved reflectivity, a method for manufacturing the same, and a perovskite solar cell comprising the same, wherein the reflectivity is improved by a surface coating of carbon nanotubes, moisture penetration is prevented, and incomplete contact is improved to increase the photoelectric conversion efficiency of the perovskite solar cell.

[0002] Solar cells have evolved from silicon solar cells to thin films and, more recently, to perovskite solar cells for sustainable development, including reducing dependence on fossil fuels, achieving carbon neutrality, and responding to climate change.

[0003] Perovskite solar cells are attracting attention as a next-generation solar cell technology because they are thin, lightweight, and flexible, offering a wide range of applications as well as excellent photoelectric conversion efficiency. Perovskites form electrons and holes upon receiving light, but charge loss can occur due to the difference in work functions between the metal and organic / inorganic active layers depending on the composition of the solar cell. To date, perovskite solar cells have been manufactured by sequentially stacking a substrate, an electron transport layer and / or a hole transport layer, a perovskite layer, an electron transport layer and / or a hole transport layer, and a metal electrode.

[0004] Metal electrode layers are characterized by their ability to prevent corrosion caused by oxidation and their good conductivity. Gold is particularly commonly used for metal electrode layers. However, metal electrodes made of metals including gold can cause degradation due to ions generated from perovskite, which can reduce long-term stability. Additionally, they are heavy and expensive, making mass production and commercialization difficult.

[0005] Consequently, carbon nanotube electrodes have recently been attracting attention as electrodes for solar cells. Carbon nanotube electrodes enable efficient current transfer, offer excellent long-term stability due to superior mechanical strength, and perform well in high-power energy devices thanks to their relatively fast electron mobility. Furthermore, their strong chemical resistance makes them advantageous for corrosion prevention, and their lightweight yet high strength makes them suitable for large-area applications in various fields.

[0006] However, replacing conventional gold electrodes with carbon nanotube electrodes leads to increased resistance, a decrease in work function, and reduced efficiency due to lower reflectivity resulting from lower current density. Furthermore, unstable contact with the Hole Transport Layer (HTL) caused by the rough surface exacerbates the resulting low reflectivity, and the electrodes have exhibited lower conductivity compared to gold electrodes to date. Additionally, the porous structure of carbon nanotubes causes moisture penetration, which was observed to result in an overall decrease in the photoelectric conversion efficiency of the solar cell.

[0007] Therefore, there is a need for technological development regarding electrodes utilizing carbon nanotubes capable of improving reflectivity, ensuring safe contact through surface improvement, enhancing electrical conductivity, and preventing moisture penetration, methods for manufacturing the same, and perovskite solar cells containing the same.

[0008] As background technology of the present invention, Korean registered patent No. 1873240 describes a perovskite solar cell and a method for manufacturing the same.

[0009] The objective of the present invention is to provide a carbon nanotube electrode for a perovskite solar cell that improves reflectivity, electrical conductivity, etc., enhances the contact rate between the carbon nanotube and the hole transport layer, and minimizes moisture penetration.

[0010] Another objective of the present invention is to provide a method for manufacturing a carbon nanotube electrode for a perovskite solar cell that improves reflectivity, electrical conductivity, etc., enhances the contact rate between the carbon nanotube and the hole transport layer, and minimizes moisture penetration.

[0011] Another objective of the present invention is to provide a perovskite solar cell utilizing a carbon nanotube electrode that can improve the photoelectric conversion efficiency of the perovskite by improving reflectivity, electrical conductivity, etc., enhancing the contact rate between the carbon nanotube and the hole transport layer, and minimizing moisture penetration.

[0012] Other objects and advantages of the present invention will become more apparent from the following detailed description of the invention, claims, and drawings.

[0013] According to one aspect, a carbon nanotube electrode for a perovskite solar cell is provided, comprising a carbon nanotube electrode having a reflective coating layer coated with copper or reduced graphene oxide on at least one aspect, and having a reflectivity of 10% or more.

[0014] According to one embodiment, the reflective coating layer of the carbon nanotube electrode may be provided on the side in contact with the hole transport layer.

[0015] According to one embodiment, the carbon nanotube electrode may have a copper coating layer having a thickness of 10 nm to 100 nm.

[0016] According to one embodiment, the carbon nanotube electrode may have a sheet resistance value of 1.1 ohm / sq or less.

[0017] According to one embodiment, the carbon nanotube electrode may have a copper coating layer formed by electroless plating.

[0018] According to another aspect, a method for manufacturing a copper-carbon nanotube electrode for a perovskite solar cell is provided, comprising: 1) a carbon nanotube preparation step of preparing carbon nanotubes; 2) a catalyst treatment step of treating the carbon nanotubes with a plating catalyst; 3) a heat treatment step of heat treating to induce crosslinking of the catalyst-treated carbon nanotubes; and 4) a reflective coating layer formation step of forming a reflective coating layer by plating copper on the surface of the heat-treated carbon nanotubes.

[0019] According to one embodiment, step 2) may include mixing distilled water and a metal catalyst solution, and supporting carbon nanotubes in a solution mixed with one or more of polyacrylic acid, polyglycol, polyaspartic acid, polyvinyl alcohol, citric acid, and polyaniline.

[0020] According to one embodiment, step 3) may include heat-treating the carbon nanotubes at 150°C to 200°C for 15 to 60 minutes.

[0021] According to one embodiment, step 4) may include electroless plating of the heat-treated carbon nanotube in a copper plating bath for 15 to 60 minutes to form a reflective coating layer on one side of the carbon nanotube.

[0022] According to another aspect, a method for manufacturing a carbon nanotube electrode for a perovskite solar cell is provided, comprising: i) a carbon nanotube preparation step for preparing carbon nanotubes; ii) a graphene oxide preparation step for preparing graphene oxide; iii) a reflective coating layer formation step for forming a graphene oxide reflective coating layer on the surface of the carbon nanotubes; and iv) a heat treatment step for heat treating the carbon nanotubes having the reflective coating layer formed thereon.

[0023] According to one embodiment, in step ii), the graphene oxide may be prepared as a dispersion diluted in water at a concentration of 0.5 wt% to 2 wt%.

[0024] According to one embodiment, the heat treatment step of step iv) may include heat treatment at a temperature of 100°C or higher at a heating rate greater than 0°C / min and less than or equal to 50°C / min.

[0025] According to another aspect, a perovskite solar cell with improved reflectivity is provided, comprising a substrate, an electron transport layer formed on the substrate, a perovskite layer formed on the electron transport layer, a hole transport layer formed on the perovskite layer, and a carbon nanotube electrode layer formed on the hole transport layer and comprising a carbon nanotube electrode for a perovskite solar cell as described herein.

[0026] According to one embodiment, the reflective coating layer of the carbon nanotube electrode may be provided on the side in contact with the hole transport layer.

[0027] According to one embodiment, one or more of the power conversion efficiency (PCE) and electrical conductivity may be improved.

[0028] According to one embodiment, the carbon nanotube electrode for a perovskite solar cell with improved reflectivity of the present invention can improve reflectivity, electrical conductivity, etc. by coating copper or graphene oxide on the surface of the carbon nanotube to reduce sheet resistance, improve the contact rate between the carbon nanotube and the hole transport layer, and improve long-term stability by minimizing moisture penetration.

[0029] According to one embodiment, the method for manufacturing a carbon nanotube electrode for a perovskite solar cell with improved reflectivity according to the present invention can improve reflectivity, electrical conductivity, etc. by coating copper or graphene oxide on the surface of carbon nanotubes to reduce sheet resistance, improve the contact rate between carbon nanotubes and a hole transport layer, and improve long-term stability by minimizing moisture penetration.

[0030] According to one embodiment, the perovskite solar cell of the present invention includes a carbon nanotube electrode coated with copper or graphene oxide on the surface of the carbon nanotube, thereby reducing sheet resistance, improving reflectivity and electrical conductivity, improving the contact rate with the hole transport layer, minimizing moisture penetration to improve long-term stability, and improving photoelectric conversion efficiency.

[0031] FIG. 1 is a schematic diagram showing a perovskite solar cell including a carbon nanotube electrode for a perovskite solar cell according to one embodiment of the present invention.

[0032] Figure 2 is a photograph showing the surface change of a carbon nanotube electrode (film) according to the Cu plating time in one embodiment of the present invention.

[0033] Figure 3 is a photograph showing the surface of a carbon nanotube, a carbon nanotube coated with graphene oxide (GO), or a carbon nanotube coated with reduced graphene oxide (rGO).

[0034] FIG. 4 is a graph showing the reflectance of carbon nanotubes coated with copper or reduced graphene oxide according to one embodiment of the present invention.

[0035] FIG. 5 is a graph showing the photoelectric conversion efficiency of a perovskite solar cell comprising an uncoated carbon nanotube electrode or a carbon nanotube coated with copper or reduced oxide according to one embodiment of the present invention.

[0036] The object, specific advantages, and novel features of the present disclosure will become more apparent from the following detailed description and embodiments in conjunction with the accompanying drawings.

[0037] Prior to this, terms and words used in this specification and claims should not be interpreted in their ordinary and dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of this disclosure, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0038] In this specification, where a component, such as a layer or part, is described as being "connected" or "combined" to another component, it may be directly "connected" or "combined" to another component, or it may have one or more other components interposed between the two components. In contrast, where a component is described as being "directly connected" or "directly combined" to another component, no other components may be interposed between the two components.

[0039] The terms used herein are merely for describing specific embodiments and are not intended to limit the disclosure. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0040] In this specification, terms such as “comprising” or “having” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should not be understood as precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0041] In this specification, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, throughout the specification, "on" means located above or below the subject part, and does not necessarily mean located on the upper side with respect to the direction of gravity.

[0042] The present disclosure is capable of various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present disclosure to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the present disclosure. In describing the present disclosure, if it is determined that a detailed description of related prior art may obscure the essence of the present disclosure, such detailed description is omitted.

[0043] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In describing with reference to the accompanying drawings, identical or corresponding components are given the same reference numerals, and redundant descriptions thereof will be omitted.

[0044]

[0045] Hereinafter, the structure of an embodiment of the present invention will be described in detail with reference to the attached drawings.

[0046] FIG. 1 is a schematic diagram showing a perovskite solar cell including a carbon nanotube (CNT) electrode layer (500) for a perovskite solar cell according to one embodiment of the present invention.

[0047] Referring to FIG. 1 and FIG. 4, a carbon nanotube electrode layer (500) for a perovskite solar cell according to one aspect of the present invention comprises a carbon nanotube electrode having a reflective coating layer (510) coated with copper or reduced graphene oxide on at least one side, and has a reflectivity of 10% or more.

[0048] Although not limited thereto, if the copper-coated reflective coating layer (510) is provided, the reflectivity is increased, the contact area with the hole transport layer (400) is widened by the surface coating, moisture penetration is minimized to improve long-term stability, and electrical conductivity can be increased.

[0049] Although not limited thereto, if a reflective coating layer (510) coated with the above-mentioned reduced graphene oxide is provided, the reflectivity is increased and moisture penetration is reduced, thereby increasing long-term stability, and the contact area with the hole transport layer (400) is widened by the surface coating, thereby increasing durability and overall performance.

[0050] Although not limited thereto, the reflective coating layer (510) of the carbon nanotube electrode may be provided on the side in contact with the hole transport layer (400). According to the configuration in which the reflective coating layer (510) of the carbon nanotube electrode is provided in contact with the hole transport layer (400) as described above, compared to the case where copper is exposed to the outside, the exposure of copper or reduced graphene oxide is minimized, thereby preventing oxidation problems.

[0051]

[0052] Although not limited thereto, the carbon nanotube electrode layer (500) may have a copper coating layer having a thickness of 10 nm or more. If the carbon nanotube electrode is less than 10 nm, it may be difficult to sufficiently store and transmit electrons as an electrode. Although not limited thereto, the thickness of the carbon nanotube electrode layer (500) may preferably be 10 nm or more and 100 nm or less, and may be more preferably 10 nm or more and 50 nm or less. If the carbon nanotube electrode layer (500) exceeds 100 nm, light transmission to the perovskite layer may not be sufficient, and the photoelectric conversion efficiency may actually decrease.

[0053]

[0054] Although not limited thereto, the carbon nanotube electrode layer (500) may have a sheet resistance value of 1.1 ohm / sq or less. In particular, when using a copper-coated carbon nanotube electrode layer (500), it may have a sheet resistance value of up to 0.02 ohm / sq or less. A low sheet resistance value may imply that the electrode is electrically efficient, that current generation efficiency and power conversion efficiency can be improved by rapidly transferring charge, that the long-term stability of the solar cell can be improved by reducing electrical and heat losses, that high-speed response is possible so that output can be transmitted quickly, and that cost efficiency can be increased due to a reduction in weight and material because the thickness of the electrode is thin overall.

[0055]

[0056] Although not limited thereto, the carbon nanotube electrode layer (500) may have a copper coating layer formed by electroless plating. When the copper coating layer is formed by electroless plating, the plating thickness can be formed evenly and uniformly, and it can help improve physical and chemical properties such as corrosion prevention, corrosion resistance, and heat resistance of copper. In addition, unlike electroplating, plating may be possible on non-metallic / non-conductive materials that are not conductive.

[0057]

[0058] According to one aspect of the present invention, a method for manufacturing a copper-carbon nanotube electrode for a perovskite solar cell of the present invention comprises: 1) a carbon nanotube preparation step of preparing carbon nanotubes; 2) a catalyst treatment step of treating the carbon nanotubes with a plating catalyst; 3) a heat treatment step of heat treating to induce crosslinking of the catalyst-treated carbon nanotubes; and 4) a reflective coating layer (510) formation step of plating copper on the surface of the heat-treated carbon nanotubes to form a reflective coating layer (510).

[0059] Although not limited thereto, the carbon nanotube preparation step of step 1) above may include a step of cutting and fixing the carbon nanotube to an appropriate size.

[0060] Although not limited thereto, the catalyst treatment step of step 2) above may include mixing distilled water or water with a metal catalyst solution and supporting carbon nanotubes in a polymer resin solution mixed with one or more of polyacrylic acid, polyglycol, polyaspartic acid, polyvinyl alcohol, citric acid, and polyaniline. Preferably, Pallyst08 (CT-1) may be used as the metal catalyst solution, and the polymer resin solution mixed with one or more of polyacrylic acid, polyglycol, polyaspartic acid, polyvinyl alcohol, citric acid, and polyaniline may be dissolved to a concentration of 1 wt% to 3 wt%. Although not limited thereto, the process may further include a step of immersing carbon nanotubes in the solution for 5 to 20 minutes and then washing with distilled water.

[0061] Although not limited thereto, step 3) above may include a process of heat-treating carbon nanotubes at 150°C to 200°C for 15 to 60 minutes. Although not limited thereto, a heat treatment time of 15 to 30 minutes may be more preferable. Although not limited thereto, if heat treatment is performed at 150°C or for less than 15 minutes, sufficient cross-linking of the polymer resin may not occur, and if heat treatment is performed at 200°C or for more than 60 minutes, cross-linking of the polymer resin may occur and then unravel, which may not be desirable.

[0062] Referring to FIG. 2, step 4) may include electroless plating of the heat-treated carbon nanotube in a copper plating bath for 15 to 60 minutes to form a reflective coating layer (510) on one side of the carbon nanotube. Although not limited thereto, the plating bath may be used by heating MSMID-80 ​​to 20°C to 70°C. Although not limited thereto, the electroless plating may be performed while the plating bath is in contact with one side of the carbon nanotube. Although not limited thereto, when electroless plating is performed, the plating thickness can be formed evenly and uniformly, and it may help improve physical and chemical properties such as copper corrosion prevention, corrosion resistance, and heat resistance. In addition, unlike electroplating, plating may be possible on non-metallic / non-conductive materials that are not conductive.

[0063]

[0064] According to another aspect of the present invention, a method for manufacturing a reduced graphene oxide-carbon nanotube electrode for a perovskite solar cell comprises: i) a carbon nanotube preparation step of preparing carbon nanotubes; ii) a graphene oxide preparation step of preparing graphene oxide; iii) a reflective coating layer formation step of forming a graphene oxide reflective coating layer (510) on the surface of the carbon nanotubes; and iv) a heat treatment step of heat-treating the carbon nanotubes on which the reflective coating layer (510) is formed.

[0065] Although not limited thereto, the carbon nanotube preparation step of step i) above may include a carbon nanotube washing step, a size adjustment step, etc.

[0066] Although not limited thereto, step ii) above may include preparing graphene oxide as a dispersion diluted in water at a concentration of 0.5 wt% to 2 wt%. Although not limited thereto, if the graphene oxide is included in an amount less than 0.5 wt%, a sufficient coating may not occur on the carbon nanotubes, and if it exceeds 2 wt%, no significant difference in the result may occur, which may result in cost inefficiency.

[0067] Although not limited thereto, step iii) above is a step for forming a reflective coating layer (510) by forming a graphene oxide reflective coating layer on the surface of the carbon nanotube, and may include applying the graphene oxide dispersion prepared in step ii) to the carbon nanotube to coat it. The coating method may use blade coating, and the coating method will not be limited to any method that allows for a thin and uniform coating, such as spray coating, dip coating, or roll-to-roll coating. Most preferably, when coating using the Dr. blade method, a thin and uniform coating can be achieved with simple equipment.

[0068] Although not limited thereto, the heat treatment step of step iv) above may include heat treatment at a temperature of 100°C or higher at a heating rate greater than 0°C / min and less than or equal to 50°C / min. If the heating rate is greater than 50°C / min or the temperature is less than 100°C, sufficient coating may not be achieved, or the bonding structure may break after coating, which may instead reduce the durability of the coating.

[0069]

[0070] A perovskite solar cell with improved reflectivity according to another aspect of the present invention comprises a substrate (100), an electron transport layer (200) formed on the substrate, a perovskite layer (300) formed on the electron transport layer (200), a hole transport layer (400) formed on the perovskite layer (300), and a carbon nanotube electrode layer (500) formed on the hole transport layer (400) and comprising a carbon nanotube electrode for a perovskite solar cell as described in the present invention.

[0071] Although not limited thereto, the substrate (100) may be formed from various materials. For example, it may be a transparent substrate containing glass or plastic material, a metal substrate such as ceramic, stainless steel, or alumina, or a flexible substrate containing polymer, etc. The substrate may be transparent or translucent for light transmission and may provide mechanical and thermal stability, and the type thereof is not limited thereto. Although not limited thereto, an electrode layer may be further formed on the substrate (100). In a solar cell, the electrode layer may be transparent so that light can reach the light absorption layer and has high conductivity. Although not limited thereto, it may include ITO, IZO, FTO, ATO, Tin Oxide, and Zinc Oxide. Although not limited thereto, the electrode layer may be included in the electron transport layer (200).

[0072] Although not limited thereto, the electron transport layer (200) is formed on the substrate (100) or the perovskite layer (300) and may include TiO2, ZnO, SnO2, CeO2, ITO, IZO, FTO, ATO, Tin Oxide, Zinc Oxide, or N-type carbon nanotubes. The electron transport layer (200) moves electrons generated in the perovskite layer (300) to the electrode and prevents the coupling of electrons and holes, thereby increasing the photo-conversion efficiency.

[0073] Although not limited thereto, the perovskite layer (300) is formed on an electron transport layer (200), a hole transport layer (400), or a carbon nanotube electrode layer (500) and may include Pbl2, FAl, MAPbBr3, MACl, MAPbI, CsPbI3, or CH3NH3Pbl3. The perovskite layer (300) has the advantage of being able to easily control the movement and recombination of electrons and holes, and can accumulate electrons and holes, resulting in a long lifespan and high photoelectric efficiency. In addition, compared to silicon solar cells, perovskite solar cells have the characteristics of having a low solution process and a thin thickness, which reduces limitations on application fields.

[0074] Although not limited thereto, the hole transport layer (400) is formed on a perovskite layer or a carbon nanotube electrode layer (500) to effectively transport holes, thereby preventing the recombination of electrons and holes and enabling efficient transport of charge. Although not limited thereto, the hole transport layer (400) may include Spiro-OMeTAD, PEDOT:PSS (Poly(3,4-ethylenedioxythiophene), polystyrene sulfonate), PTAA (Poly(triarylamine)), P-type carbon nanotubes, etc., and will not be limited to any type of material as long as it has excellent conductivity and stability, is transparent, and is easy to process.

[0075] Although not limited thereto, the carbon nanotube electrode layer (500) may include a carbon nanotube electrode, and a reflective coating layer (510) of the carbon nanotube electrode may be further provided on the surface in contact with the hole transport layer (400). Considering that conventional carbon nanotube electrodes have low reflectivity, the reflective coating layer (510) is additionally configured to allow light refraction to occur one or more times, and in the present invention, it may be coated with copper or reduced graphene oxide.

[0076] Although not limited thereto, if the copper-coated reflective coating layer (510) is provided, the reflectivity is increased, the contact area with the hole transport layer (400) is widened by the surface coating, the reflectivity is increased, and the conductivity can be increased compared to the gold electrode. Additionally, although not limited thereto, the reflective coating layer (510) of the carbon nanotube electrode may be provided on the side in contact with the hole transport layer (400). According to the configuration in which the reflective coating layer (510) of the carbon nanotube electrode is provided to be in contact with the hole transport layer (400) as described above, compared to the case where copper is exposed to the outside, the exposure of copper or reduced graphene oxide is minimized, thereby preventing oxidation problems.

[0077] Although not limited thereto, if a reflective coating layer (510) coated with the above-mentioned reduced graphene oxide is provided, the reflectivity is increased and moisture penetration is reduced, thereby increasing long-term stability, and the contact area with the hole transport layer (400) is widened through the surface coating, thereby increasing durability and overall performance.

[0078]

[0079] Although not limited thereto, a perovskite solar cell with improved reflectivity manufactured by the method described herein may have one or more of improved power conversion efficiency (PCE) and electrical conductivity. The present invention may further include a reflective coating layer (510) coated with copper or reduced graphene oxide as described above to improve reflectivity, prevent moisture penetration, and improve incomplete contact, thereby increasing the electrical conductivity and photovoltaic conversion efficiency of the perovskite solar cell.

[0080]

[0081] Examples

[0082] Example 1. Preparation of copper-carbon nanotube film

[0083] 1-1. Pretreatment for Unilateral Plating

[0084] A CNT fiber film was attached to one hole of a column-shaped Teflon fixture, which has a length similar to a plating solution reaction vessel and is open at both ends, and the side was sealed to prevent the solution from passing through.

[0085] 1-2. Catalyst Treatment for Plating

[0086] Distilled water and the metal catalyst solution Pallyst-8 (CT-1) were mixed in a ratio of 9:1, and polyacrylic acid (molecular weight: 250,000) resin was dissolved in the solution to a concentration of 1.7 wt%. A CNT fiber film was immersed in this solution for 10 minutes, removed, and then washed with distilled water.

[0087] 1-3. Heat Treatment

[0088] The CNT fiber film was heat-treated at 180°C for 30 minutes to induce crosslinking of the polymer resin.

[0089] 1-4. Metal Plating

[0090] The plating bath used for plating was MSMID-80 ​​(MSC Co., Ltd.) heated to 45°C. A catalyst-treated CNT fiber film was placed in the plating bath, and distilled water heated to 45°C was added to the inside of a Teflon fixture. Electroless plating was performed with one side in contact with the plating bath, and the film was washed with distilled water. The plating time was set to 10, 20, and 30 minutes to control the plating degree.

[0091]

[0092] Example 2. Preparation of reduced graphene oxide (rGO)-carbon nanotube electrode

[0093] 2-1. Preparation of Carbon Nanotube Electrode

[0094] A carbon nanotube electrode was prepared in a desired size. In Example 2, it was prepared in a size of 10*10cm.

[0095] 2-2. Graphene Oxide Coating

[0096] A dispersion of graphene oxide (GO) dispersed in water at a concentration of 1 wt% was applied to the carbon nanotube electrode and then coated using a Dr. blade.

[0097] 2-3. Heat Treatment

[0098] A carbon nanotube electrode coated with graphene oxide was heat-treated under the following conditions to produce a carbon nanotube electrode coated with graphene oxide (GO) (Comparative Example) and a carbon nanotube electrode coated with reduced graphene oxide (rGO) (Example 2).

[0099] - 5℃ / min 60℃ vacuum 1hr → GO@CNT electrode fabrication (Comparative Example)

[0100] - 1℃ / min 300℃ air 1hr → Preparation of rGO@CNT electrode (Example 2)

[0101]

[0102] Example 3. Preparation of a perovskite solar cell

[0103] 3-1. Substrate Manufacturing Step

[0104] FTO glass was prepared as a transparent substrate.

[0105] 3-2. Cathode Electrode Manufacturing Step

[0106] Titanium diisopropoxide bis(acetylacetonate) was dissolved in ethanol at a concentration of 7.5 wt%, sprayed onto FTO glass, and then heat-treated at 450°C to prepare a TiO2(c-TiO2) layer.

[0107] 3-3. Electron Transport Layer Manufacturing Step

[0108] A solvent was prepared by mixing terpineol and 2-Me in a ratio of 1:3.5 wt%, and TiO2 paste was dissolved in the prepared solvent in a ratio of 1:5 wt%. The prepared meso-TiO2 solution was filtered through a 0.45 μm PVDF filter, and then spin coating was performed at 2500 rpm for 50 seconds after loading 85 μm. After evaporating the solvent at 150°C, heat treatment was performed at 500°C for 1 hour.

[0109] 3-4. Perovskite Layer Manufacturing Step

[0110] A perovskite precursor solution was prepared by dissolving PbI2 1.60M, FAI 1.47M, MAPbBr3 0.07M, and MACI 0.53M in a solution of DMF and DMSO (8:1 v / v). Subsequently, the perovskite precursor solution was spin-coated onto a TiO2 (c-TiO2) layer at 500 rpm for 5 seconds, and heat-treated at 150°C for 10 minutes to form a perovskite layer.

[0111] The manufactured perovskite film was washed with IPA while rotating at 5000 rpm.

[0112] 3-5. Hole Transport Layer Manufacturing Step

[0113] 100 mg of spiro-OMeTAD, 23 μL of Li-TFSI (540 mg / mL acetonitrile), 39 μL of tBP, and 10 μL of Co(III) salt solution (376 mg / mL acetonitrile) were dissolved in 1.1 mL of chlorobenzene to prepare a hole transport layer. The prepared solution was spin-coated at 2000 rpm for 3 seconds to fabricate a hole transport layer.

[0114] 3-6. Carbon Nanotube Electrode Manufacturing Steps

[0115] A carbon nanotube electrode was prepared by placing free-standing carbon nanotubes prepared according to Examples 1 and 2 on a hole transport layer and pressing them.

[0116]

[0117] Experimental Example

[0118] Experimental Example 1. Analysis of Surface Changes of Carbon Nanotube Electrode (Film) According to Cu Plating Time

[0119] Figure 2 is a diagram showing the surface change of a carbon nanotube electrode (film) according to the Cu plating time of the carbon nanotube.

[0120] Referring to Example 1 and Fig. 2, it can be seen that the surface of the carbon nanotube electrode (film) changes depending on the Cu plating time. According to Fig. 2, it was confirmed that the surface change of the carbon nanotube electrode (film) was best when plating (heat treatment) was performed for 30 minutes.

[0121]

[0122] Experimental Example 2. Analysis of Surface Changes of Graphene Oxide Coated Electrodes According to Temperature and Conditions

[0123] Figure 3 is a diagram showing the surface of a carbon nanotube, a carbon nanotube coated with graphene oxide (GO), or a carbon nanotube coated with reduced graphene oxide (rGO).

[0124] Referring to Example 2 and Fig. 3, it was confirmed that the surface of the carbon nanotubes differed depending on the temperature and conditions. Graphene oxide (GO)-carbon nanotube electrodes were prepared by heat treatment under vacuum conditions of 60°C at 5°C / min for 1 hr, and reduced graphene oxide (rGO)-carbon nanotube electrodes were prepared by heat treatment under air conditions of 300°C at 1°C / min for 1 hr. That is, when heat treated in a high-temperature atmosphere of 300°C, a reduction process occurred, and reduced graphene oxide (rGO) was coated. It was confirmed that the surface of the carbon nanotubes became brighter in the order of untreated carbon nanotubes, carbon nanotubes coated with graphene oxide (GO), and carbon nanotubes coated with reduced graphene oxide (rGO).

[0125]

[0126] Experimental Example 3. Analysis of Reflectance Change According to Coating

[0127] Figure 4 is a graph comparing the reflectance of carbon nanotubes coated with copper or reduced graphene oxide according to Example 1 and Example 2.

[0128] According to Figure 4, the wavelength-dependent reflectance of carbon nanotubes was found to be about three times higher than that of uncoated carbon nanotubes when coated with copper or reduced graphene oxide.

[0129]

[0130] Experimental Example 4. Analysis of Change in Sheet Resistance of Carbon Nanotube Electrode According to Coating

[0131] Referring to Tables 1 and 2, it can be seen that the sheet resistance of the carbon nanotube electrodes is lowered after coating with copper or reduced graphene oxide. Therefore, as the sheet resistance of the carbon nanotube electrodes decreases, the electrical conductivity of the carbon nanotube electrodes increases, which can increase the photoelectric conversion efficiency of the solar cell. In particular, it can be seen that copper-coated carbon nanotubes have the best sheet resistance value when plated (heat treated) for 30 minutes.

[0132]

[0133]

[0134] Experimental Example 5. Analysis of Solar Cell Photovoltaic Conversion Efficiency

[0135] The photoelectric conversion efficiency of the solar cell according to the present invention was analyzed and is shown in Figure 5 and Table 3.

[0136] Referring to Figure 5 and Table 3, the photoelectric conversion efficiency of the solar cell in Example 3 was 19.42% or 19.50%, and the solar cell efficiency of the comparative example (CNT) was 17.60%, confirming that the photoelectric conversion efficiency of the solar cell was improved by approximately 2%p. Through this, it was confirmed that the electrode coating method also effectively influences the improvement of the photoelectric conversion efficiency of the solar cell.

[0137]

[0138] Although the present disclosure has been described in detail through specific embodiments, this is for the purpose of specifically explaining the present disclosure and is not limited thereto. It is evident that modifications or improvements can be made by those skilled in the art within the technical scope of the present disclosure. All simple modifications or alterations of the present disclosure fall within the scope of the present disclosure, and the specific scope of protection of the present disclosure will be clarified by the appended claims.

[0139]

[0140] [Explanation of the symbol]

[0141] 100: Substrate

[0142] 200: Electron transport layer

[0143] 300: Perovskite layer

[0144] 400: Precision Transport Layer

[0145] 500: Carbon nanotube electrode layer

[0146] 510: Reflective coating layer

Claims

1. A carbon nanotube electrode for a perovskite solar cell comprising a carbon nanotube electrode having a reflective coating layer coated with copper or reduced graphene oxide on at least one side, and having a reflectivity of 10% or more.

2. In Paragraph 1, A carbon nanotube electrode for a perovskite solar cell, wherein the reflective coating layer of the carbon nanotube electrode is provided on the side in contact with the hole transport layer.

3. In Paragraph 1, The carbon nanotube electrode for a perovskite solar cell comprises a copper coating layer having a thickness of 10 nm to 100 nm.

4. In Paragraph 1, The carbon nanotube electrode above is a carbon nanotube electrode for a perovskite solar cell having a sheet resistance value of 1.1 ohm / sq or less.

5. In Paragraph 1, The carbon nanotube electrode above is a carbon nanotube electrode for a perovskite solar cell having a copper coating layer formed by electroless plating. 6.1) Carbon nanotube preparation step for preparing carbon nanotubes; 2) A catalyst treatment step of treating the above carbon nanotubes with a plating catalyst; 3) A heat treatment step for heat treating to induce crosslinking of the catalyst-treated carbon nanotubes; and 4) a step of forming a reflective coating layer by plating copper on the surface of the heat-treated carbon nanotube to form a reflective coating layer; comprising a method for manufacturing a copper-carbon nanotube electrode for a perovskite solar cell.

7. In Paragraph 6, A method for manufacturing a copper-carbon nanotube electrode for a perovskite solar cell, wherein step 2) comprises mixing distilled water and a metal catalyst solution, and supporting carbon nanotubes in a solution mixed with one or more of polyacrylic acid, polyglycol, polyaspartic acid, polyvinyl alcohol, citric acid, and polyaniline.

8. In Paragraph 6, A method for manufacturing a copper carbon nanotube electrode for a perovskite solar cell, wherein step 3) comprises heat-treating the carbon nanotubes at 150°C to 200°C for 15 to 60 minutes.

9. In Paragraph 6, A method for manufacturing a carbon nanotube electrode for a perovskite solar cell, wherein step 4) comprises electroless plating of the heat-treated carbon nanotube in a copper plating bath for 15 to 60 minutes to form a reflective coating layer on one side of the carbon nanotube. 10.i) Carbon nanotube preparation step for preparing carbon nanotubes; ii) Graphene oxide preparation step for preparing graphene oxide; iii) a step of forming a reflective coating layer by forming a graphene oxide reflective coating layer on the surface of the carbon nanotube; and iv) a heat treatment step of heat-treating the carbon nanotube having the reflective coating layer formed thereon; comprising a method for manufacturing a carbon nanotube electrode for a perovskite solar cell.

11. In Paragraph 10, A method for manufacturing a carbon nanotube electrode for a perovskite solar cell, comprising preparing, in step ii) above, a dispersion of graphene oxide diluted in water at a concentration of 0.5 wt% to 2 wt%.

12. In Paragraph 10, A method for manufacturing a carbon nanotube electrode for a perovskite solar cell, wherein the heat treatment step of step iv) above comprises heat treatment at a temperature of 100°C or higher at a heating rate greater than 0°C / min and less than or equal to 50°C / min.

13. Substrate; An electron transport layer formed on the above substrate; A perovskite layer formed on the electron transport layer above; A hole transport layer formed on the above perovskite layer; and A perovskite solar cell with improved reflectivity comprising: a carbon nanotube electrode layer formed on the hole transport layer and including a carbon nanotube electrode for a perovskite solar cell described in claim 1.

14. In Paragraph 13, A perovskite solar cell with improved reflectivity, wherein the reflective coating layer of the carbon nanotube electrode is provided on the side in contact with the hole transport layer.

15. In Paragraph 13, A perovskite solar cell with improved reflectivity, having improved power conversion efficiency (PCE) and electrical conductivity, at least one of which is improved.

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